CVE-2026-45309: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in ronf asyncssh
AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Prior to 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.
AI Analysis
Technical Summary
AsyncSSH, a Python package implementing SSHv2 on asyncio, improperly limits pathname expansion for the AuthorizedKeysFile %u token before version 2.23.0. During pre-authentication server config reload, the raw SSH username is expanded without sanitization, allowing path traversal via characters such as /, \, or .. in the username. This enables reading authorized keys files outside the intended directory and authentication with attacker-selected keys. The vulnerability is identified as CWE-22 and has a CVSS 4.0 score of 8.2 (high severity). The issue is resolved in AsyncSSH version 2.23.0.
Potential Impact
An attacker can exploit this vulnerability by using specially crafted SSH usernames containing path traversal sequences to bypass directory restrictions on authorized keys files. This can lead to unauthorized authentication using attacker-controlled keys, potentially allowing unauthorized access to the SSH server.
Mitigation Recommendations
Upgrade AsyncSSH to version 2.23.0 or later, where this path traversal vulnerability is fixed. Since this is a software package, applying the official fix by updating to the patched version is the recommended remediation.
CVE-2026-45309: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in ronf asyncssh
Description
AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Prior to 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.
CVSS v4.0
Score 8.2high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
AsyncSSH, a Python package implementing SSHv2 on asyncio, improperly limits pathname expansion for the AuthorizedKeysFile %u token before version 2.23.0. During pre-authentication server config reload, the raw SSH username is expanded without sanitization, allowing path traversal via characters such as /, \, or .. in the username. This enables reading authorized keys files outside the intended directory and authentication with attacker-selected keys. The vulnerability is identified as CWE-22 and has a CVSS 4.0 score of 8.2 (high severity). The issue is resolved in AsyncSSH version 2.23.0.
Potential Impact
An attacker can exploit this vulnerability by using specially crafted SSH usernames containing path traversal sequences to bypass directory restrictions on authorized keys files. This can lead to unauthorized authentication using attacker-controlled keys, potentially allowing unauthorized access to the SSH server.
Mitigation Recommendations
Upgrade AsyncSSH to version 2.23.0 or later, where this path traversal vulnerability is fixed. Since this is a software package, applying the official fix by updating to the patched version is the recommended remediation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-11T20:14:43.203Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a5b5eb32d1edb114c7fb4f0
Added to database: 07/18/2026, 11:08:35 UTC
Last enriched: 07/25/2026, 22:41:53 UTC
Last updated: 09/01/2026, 10:52:09 UTC
Views: 59
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